Accurate alignment of a rotating tool to a work piece is essential in many machining operations. Because of this importance, it is estimated that in many machining operations at least 50% of the available time is devoted to set up, leaving less than 50% of available time to actual cutting or machining operations. This large amount of time, in part, is caused by the complexities and inaccuracies of most available alignment techniques and tools.
Currently most rotating machine tools and their work pieces are manually aligned with one another. In many such machining operations this manual alignment can determine with reasonable accuracy the point at which the cutting tool will make its initial contact with the work piece. For example, the cutting tool can be advanced toward the work piece until the initial contact is made. Then the work piece and/or tool can be adjusted to the desired point of initial contact.
Although the above described manual alignment is acceptable in many instances, there are other cutting or tooling operations where, because of the need for precision, simple mechanical alignment of the tool and work piece is unacceptable. More particularly, the above described manual alignment only determines the point of initial contact between the cutting tool and the work piece, and it does not determine the degree of alignment between the work piece and the axis of rotation of the machine, tool holder and tool. Imperfections in the tool or tool holder, dirt or other debris in or on the tool or tool holder, or errors by the machine operator are very common. Consequently although the tool generally is approximately aligned with the axis of rotation of the tool holder, their inevitably is some angular misalignment to and/or displacement from the rotational axis. The cutting or machining will be imprecise in all such instances when the axis of the tool is not collinear with the axis of rotation of the machine and the tool holder.
Alignment problems also can occur in machining operations where the alignment must take place at a point in a manufacturing process when the work piece and the rotating cutting tool are physically separated from one another by a considerable distance. Manual alignment also is made difficult for machine tool operations where the tool is intended to be angularly aligned to the exterior face of the work piece, or where the tool will perform a machining operation on an interior portion of the work piece, such as tapping threads on a previously smooth cylindrical bore.
Laser alignment systems have been developed which have many uses including the alignment of parts for assembling machines such as turbines. Currently systems of laser beams and targets are available to facilitate alignment of parts along an axis as well as assessment and correction of pitch and yaw. Examples of such systems and components are disclosed in U.S. Pat. No. 4,297,031 and U.S. Pat. No. 4,382,680 both of which issued to Martin R. Hamar and are entitled "APPARATUS AND PROCESS FOR SWEEPING A FLAT OPTICAL LIGHT PLANE." Such laser systems and components also are disclosed in copending application Ser. No. 381,079 filed May 24, 1982 by Martin R. Hamar and entitled "PENTA-PRISM MODULE HAVING LASER ALIGNMENT, ERROR DETECTION AND CORRECTION CAPABILITY" and application Ser. No. 381,078 filed May 24, 1982 by Martin R. Hamar and entitled "LASER MEASUREMENT SYSTEM, VIRTUAL DETECTOR PROBE AND CARRIAGE YAW COMPENSATOR." Despite the many very desireable features of the available laser or mechanical alignment devices or techniques, none have been able to efficiently and accurately enable true projection of an axis of rotation and/or quick accurate alignment of a work piece with an axis of rotation. Additionally it has been found that the mechanical alignment devices and techniques such as level lines and levels are subject to sagging and warping particularly at greater distances.
In view of the above, it is an object of the subject invention to provide an apparatus and method for accurately projecting an axis of rotation from a rotating tool to a work piece.
It is another object of the subject invention to provide an apparatus and method which enables accurate alignment of an axis of rotation in a minimum amount of time.
It is an additional object of the subject invention to provide an apparatus and method for aligning an axis of rotation which detects both angular misalignments and radial misalignments.
It is still a further object of the subject invention to provide an apparatus and method for aligning an axis of rotation which can be mounted directly in the rotating member.